Why does the Federation have no camouflage?

The Romulan cloaking device is an important piece of cloaking technology. It enables the Romulans to stalk secretly and repeatedly carry out covert attacks against enemies.

The Romulan cloaking device makes a ship invisible to both the naked eye and most sensor systems. It enables a Romulan ship or fleet to carry out an attack with virtually no warning. The constant improvements and modifications in cloaking technology are countered by increasingly sophisticated scanning equipment for the detection of cloaked ships, but an experienced Romulan commander with a well-functioning cloaking device on his ship is still a dangerous opponent.
The Romulans withdrew to their territory in 2160 after the Battle of Cheron, ending decades of war against Earth. Protected by the Neutral Zone, the Romulans are not seen for 100 years - until their dramatic return in 2266, when Starfleet realizes that the Romulan threat could be topical again. On Stardate 1709, a single Romulan Bird-of-Prey arrives in Federation space and attacks Outposts II, III, and IV along the Neutral Zone with a new powerful plasma weapon. Destroying these colonies will not only test the defensive strength of the Federation's starships and space bases, but also their response to a threat from the Star Empire. The U.S.S. Enterprise NCC-1701 is dispatched to investigate the case; under the command of Captain James T. Kirk, she attacks the Romulan ship, although the Constitution-class ship has suffered severe damage due to the use of camouflage technology.

Construction weaknesses
Romulan weapon technology has focused on cloaking devices and plasma weapons; the drive systems of the aging Romulan Birds-of-Prey were neglected. In the battle with the Enterprise, the disadvantages of the camouflage system prove to be serious. It must be deactivated during transport and will not work when the weapon systems are in use. Shields and camouflage cannot be activated at the same time, so even an indirect hit from a Federation weapon can cause enormous damage.
The destruction of the Bird-of-Prey despite its camouflage technology caused the Romulans to concentrate on improving the device. In return, Federation Security 2268 launched a covert operation to obtain an improved cloaking device. The weaknesses of the camouflage system are being investigated by naval fleet scientists and it is found that they have not been changed since the last encounter.
Inconvenient alliance

When it is realized that the cloaking device does not bring the hoped-for tactical advantage, the Romulan Star Empire enters into an uncomfortable alliance with the Klingon Empire. This is the turning point for the Romulan military: the faulty original Birds-of-Prey are being replaced by ships of the Klingon design, which can travel faster and further, accommodate more troops and also use the cloaking device. The Romulan-Klingon Alliance falls apart in 2293, but the Klingons keep the newly acquired technology,
The Romulan attitude towards the Federation was expressed again in 2311 when thousands lost their lives in a brutal battle between Romulan troops and Starfleet during the Tomed Incident. This leads to the Treaty of Algeron, which, in addition to the re-strengthening of the boundaries of the neutral zone, interestingly contains a ban on the Federation from developing its own camouflage technology. After a long period of isolation as a result of the Tomed incident, Romulan ships are being equipped with tachyon scanning sensor technology that can be used to detect certain cloaking systems. The insistence on the development ban served to preserve one's own tactical advantage.
Tactical attacks

In 2344 one of the best tactical operations in cloaking technology comes when Romulan ships launch an attack on the Klingon outpost at Narendra III. The U.S.S. Enterprise NCC-1701-C under the command of Captain Rachel Garrett is destroyed.
Two years later, a similar attack takes place on the Klingon outpost near Khitomer. In 2364, Starfleet meets the new Romulan warbird, whose systems are significantly improved. Starfleet suspects Romulan involvement in the Klingon civil war that broke out in 2368. Again, it is necessary to override the Romulan cloaking device in order to gain a tactical advantage. This leads to the development of the tachyon detector grid by chief engineer Geordi La Forge of the U.S.S. Enterprise NCC-1701-D. Twenty Federation ships are deployed to create a network of active tachyon beams; so they track down Romulan ships that support the troops of the Duras family.
New developments

To further develop the cloaking device, Romulan scientists experiment with a molecular phase inverter, which is combined with a cloaking device, but when there is a catastrophic failure of the warp core in the test ship, they revert to the tachyon-based system. The Empire's attempt in 2370 to destroy the U.S.S. Recovering Pegasus NCC-53847 and its illegal phase cloaking device could aim both to steal the technology and to expose Starfleet's violation of the Algeron Treaty.
In 2371 the Romulans loaned a cloaking device to the U.S.S. Defiant NX-74205, but do not allow their use outside the gamma quadrant. But the 'maiden' camouflage flight fails. The Defiant is recognized by Jem'Hadar ships; she is boarded and her crew is captured. In the same year, the Romulan fleet was severely decimated in an ambush on the Dominion in the Orias sector, but three years later in the Dominion War the tide turned and it became clear once again what an effective tactical weapon the Romulan cloaking device is.